التنوع الوراثي في عزلات الفطر Tilletia tritici و T. laevis مسبب مرض التفحم الشائع على القمح في العراق

الملخص EN

Common bunt disease (Tilletia tritici and T.

laevis), is one of the most destructive diseases on wheat in Iraq.

It can cause severe yield loss when susceptible cultivars are grown without chemical seed dressing.

The study was conducted in order to determine the genetic variation within the wheat common bunt pathogen isolates, through their interaction with differential varieties.

Collections of common bunt were prepared from bunt-infected spikes representing the main wheat growing areas during 2012/13 growing season.

Eighteen isolates were selected based on high germination rate of their teliospores, and used for artificial inoculation in Sulaimania.

Results revealed that there was a wide genetic diversity among the pathogen isolates representing different locations.

18 races of Tilletia tritici and T.

laevis pathogens were identified according to the international nomenclature system.

Ten of these races match with the globally registered races T1, (T1, L1, L2), T2, T4, T9, T11, T13, T17, T18 and T20, while the remainder 8 races may be new and are not globally registered.

Resistance genes Bt2, Bt6, Bt14 and Bt15 were ineffective against most of the races, while Bt1was ineffective against five races, Bt4 and Bt8 were ineffective against four races, Bt3 and Bt5 were ineffective against three races and genes Bt7, Bt9 and Bt13 were ineffective only against two races.

All the identified races could not overcome the known resistant genes Bt11 and Bt12, while only two races appeared able to overcome resistant genes Bt7, Bt9, Bt10 and Bt13.

Confirmation of the identification of these races on molecular bases is further needed.